Super Thumpy Update 11-1-99 The Auto Thumpy is a magnetic pulser described on keelynet. It uses the large party strobe from Radio Shack. After building one of those, I found that there was a resistor in series with the strobe that would get hot because of the larger capacitor that I had added. So I went out and bought the small party strobe from Radio Shack, part number 42-3048. I turned off and unplugged the unit, and then took out the 4 screws that hold the cover on, the 4 screws that hold the printed circuit board down, and the 2 screws that hold the strobe cover on. The strobe housing and chassis slip right out without disconnecting any wires. (Please do not try any of this if you do not know how to identify a capacitor or discharge it. You could be injured or worse. These strobe units are very dangerous even when not plugged in due to the charge in the capacitor.) I made sure the capacitor was discharged, and cut the wire leading to one end of the flash tube, leaving enough length on each end to attach the 4 feet of 16 gauge speaker wire that goes to the coil. The coil is MCM part number 50-940. It is important to cut a wire leading to an end, not the middle of the flash tube. The coil wire exits the box through a hole in the upper right corner of the front, just above the power cord hole. A grommet protects the cord. After attaching the coil and making sure that nothing was shorted out, I plugged in the still disassembled unit and turned it on. The pulse was rather feeble as expected. The large capacitor is a 9uf at 600 volts. I measured the voltage on the capacitor. It was just over 250. The contact near the center of the printed circuit board is the negative end. I wanted a 200 or so uf at 600 volts, but was unable to find one at Supertronix. So I settled on a 100uf at 450 volts. With the device unplugged and the capacitor discharged, I removed the capacitor and replaced it with the new one. All connections were insulated, and the coil wrapped with electrical tape, as this is an experimental magnetic pulser, not a shock therapy device. I also put black electrical tape over the clear flash tube cover. With credit cards and other magnetic material removed from the area, I tried out the modified device. Very nice pulse. Looks better than the Radio Shack strobe in the larger box. The circuit board also looks much more robust and the capacitor fires the strobe directly, so there is no series resistor overheating in this one. Much better device. More recently, I discovered that All Electronics has a 300uf at 320 volts that is physically small. So last night I put one of those in a Super Thumpy using wires that are about 3" long. Worked fine. There was plenty of room for a second one, so I added it. Very powerful pulse, but it takes about two seconds to charge. I am not sure if the tube and related parts will put up with this much power for long, so I am using one at home on a trial basis to see if it breaks. Bob Haining has designed a much more powerful pulser which I hope to be able to experiment with soon.